The principal goal of the Administrative and Biostatistics Core (Core A) is to provide the essential operational plan and organizational structure to facilitate the continued success of the U19. This will be accomplished by coordinating both scientific and logistical issues for the individual Projects and the Transplant Pathology and Tissue Imaging Core (Core B), their interactions to enhance conceptual unity and Program synergy and the U19 as a whole. The Core will coordinate communication and scientific meetings between the Program Director (PD), Project Leaders (PLs), Co-Investigators and the Leader of Core B to facilitate scientific collaboration, project interaction, and data sharing,- each important goals of the U19. The Core will also co- ordinate data and statistical input for each of the Projects through a faculty biostatistician. It will provide logistical assistance for preparation of reports (including annual milestone reports), compliance and regulatory issues, grant renewal, and abstract and manuscript submissions. Also, by providing financial oversight, the Core will maximize the responsible and efficient use and allocation of funds, thus fulfilling obligations to the University of Pittsburgh and the NIAID. In executing these functions, the Core will also allow the PD, PLs, Core B Leader and Co-Investigators more time to address their research goals. An additional important function of the Core will be to co-ordinate communication with the NIAID and NHPCSG Steering Committee.